While the simplicity of a great sound can certainly be enough – as evidenced by HD600’s staying power – subtle evolutions, like the HD660S, help move the brand forward and remain relevant in the current landscape. According to Sennheiser, the airflow around the transducer has been optimized, resulting in a greater sensitivity.

The one big different is the driver assembly, which is completely different and not interchangeable. Parts such as hand claps and hi hats take on a much more forward and risky character, while synths find some extra teeth in their buzzy overtones.While the imaging does provide generally excellent positioning and weight, it doesn’t feel fully three dimensional and doesn’t strongly present the center of the stereo image in front of the listener. I'll not wax poetic this time regarding the long and storied history and my experiences with the HD 6xx family of Sennheiser headphones. In the extreme, it can have the tonal effect of sounding like a vocalist is speaking or singing through a toilet paper tube or cupping their hands over their mouth.

See our recommendations for the best audiophile headphones, the best wired headphones, and the best headphones for studio use. Update: 08/12/2019 After comparing these headphones with other models, we found them to be very tight and reduced their score accordingly. Like the finish, the sound comes down to a matter of taste, but I would actually give a slight edge to the HD650 as a matter of personal preference. So far what I did is I increased bass to the maximum via the Mojo 2, maxed out the red light on the Mojo 2 (sub-bass) and the yellow light (bass), and I found some of my music in Hi-Res, 96 KHz / 24 bit is the maximum quality that I found, but only very few of my favorite music is available in that quality.On the other hand, HD660S has a wider soundstage and I perceived aspects of the imaging as being stronger, while HD650 is narrower, but has a stronger sense of center imaging. Regarding phones, I used to have the LG V20 that had a built in Quad DAC, now I have a cheap Redmi phone, but thinking to get the Sony Xperia Pro that “supports Hi Res music” or the Samsung Galaxy S23 ultra that explicitly supports 32 bit / 768 KHz music. They have an integrated mic, good onboard controls, and a more bass-rich sound profile that some listeners may prefer.